I wonder how many hours people think they will put on their genset? A low-RPM diesel is great if you are completely off grid and want to run the generator 12-24 hours a day. For standby power it is only practical if you run enough fuel through your tractor to keep it from sludging in the tank.
For standby power where the generator will sit a year or two between uses, propane (or natural gas if you have it) is by far the best fuel source. Mine says it will run 8 hours at 50% on a 20 lb. tank, so I bought a 100 lb. tank. It will be fine for the next 20 years, and will give me 40 hours of run time, more or less, before I have to start swapping little tanks.
Gasoline is the best for portable power in the field or to construction sites, because the equipment is light weight and and you can buy fuel anywhere. I saw a 5 hp Honda on an Emglo compressor run a large construction crew 8 hours a day, 5 days a week, for 5 years. We changed the oil once a month and the spark plug once a year. It was still running fine when I moved on. Contrary to popular opinion, Briggs and Stratton engines also have outstanding reliability. The only one I have ever had quit on me was 40 years old, and it only quit because carbon lodged in a valve. The Vanguard engines with full flow oil filters are outstanding power plants. If the engine is going to sit for years between uses, stay away from gasoline. The fuel is not stable and it will clog the carb.